The subject invention is directed toward the art of electric bus bar assemblies and, more particularly, to the art of low impedance laminated bus bars of the type used in electronic power conversion circuits.
The invention is especially useful in the electric variable speed motor drive industry as a low impedance bus arrangement for inverters and will be described with reference thereto; however, the invention could be used in other environments and for many different purposes.
Prior high power laminated bus assemblies for electrical switching converters have typically comprised substantially planar laminated bus structures. An example of one such structure is described in U.S. Pat. No. 5,365,424 to Deam, et al. The structure described there includes a plurality of dielectric layers interposed between flat conductive layers. Three flat AC bar conductors are arranged in the same conductive layer as a mid-point bus connecting a plurality of capacitors. A -DC bar conductor is stacked on the AC bar conductors and mid-point bus but separated therefrom with a dielectric layer made of G-10 material. A substantially flat +DC bar conductor is arranged on the -DC bar conductor and spaced therefrom by a similar dielectric layer formed of G-10 material.
The Deam, et al. patent described briefly above is typical of the many high power laminated bus assemblies available for electrical switching converters. In general, the prior art laminated bus assemblies are quite limited both mechanically and electrically due mainly to the flat conductive layers. In that regard, subsequent to the flat conductive layers being laminated together, it has heretofore been impossible to bend, form, or otherwise work the laminated structure without disturbing the mechanical and electrical integrity of the dielectric layers interposed between the respective conductive layers. Therefore, prior art laminated bus assemblies such as the one shown in Deam, et al. have been constrained to a flat or planar configuration.
While these prior designs are generally satisfactory, its is desirable to bend the laminated bus structure into various contoured configurations in order to save space and to lend flexibility to the power converter design. In addition, it is desirable to provide a contoured electric bus bar which has an inherently low impedance characteristic so as to not require additional passive "snubber" circuits.